dm: core: Create a new header file for 'compat' features

At present dm/device.h includes the linux-compatible features. This
requires including linux/compat.h which in turn includes a lot of headers.
One of these is malloc.h which we thus end up including in every file in
U-Boot. Apart from the inefficiency of this, it is problematic for sandbox
which needs to use the system malloc() in some files.

Move the compatibility features into a separate header file.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/usb_hub.c

@@ -26,6 +26,7 @@
 #include <dm.h>
 #include <env.h>
 #include <errno.h>
+#include <malloc.h>
 #include <memalign.h>
 #include <asm/processor.h>
 #include <asm/unaligned.h>